Re: "homology / similarity" of proteins

John Walshaw (
Fri, 24 May 1996 20:14:42 +0100 (BST)

On Fri, 24 May 1996, William Pitt wrote:

> John tells me that there are serine proteases with completely different
> folds but with very similar active site geometry but that this is
> considered to have occured due to convergent rather than divergent
> evolution.

There are two major families in this class, the mammalian trypsin family
and the bacterial subtilisins, which have very similar active sites, but
which "..are not otherwise *detectably* related, and provide one of the
most striking examples of *apparent* evolutionary convergence" (my
asterisks)- from "Proteins", Creighton. In Branden and Tooze it is
described as "a classical example of convergent evolution at the molecular

I seem to remember reading/hearing somewhere that there may be evidence
that the two families share a common ancestor with this active site... am
I remembering correctly? Can anyone offer any insight?

John Walshaw